Long-term Memory Processes Research Articles

Regional Hurst Exponent Reflects Impulsivity-Related Alterations in Fronto-Hippocampal Pathways Within the Waiting Impulsivity Network.

In general, the Hurst exponent. is used as a measure of long-term memory of time series. In previous neuroimaging studies, H has been introduced as one important parameter to define resting-state networks, reflecting upon global scale-free properties emerging from a network. H has been examined in the waiting impulsivity (WI) network in an earlier study. We found that alterations of H in the anterior cingulate cortex (HACC) and the nucleus accumbens (HNAcc) were lower in high impulsive (highIMP) compared to low impulsive (lowIMP) participants. Following up on those findings, we addressed the relation between altered fractality in HACC and HNAcc and brain activation and neural network connectivity. To do so, brain activation maps were calculated, and network connectivity was determined using the Dynamic Causal Modeling (DCM) approach. Finally, 1–H scores were determined to quantify the alterations of H. This way, the focus of the analyses was placed on the potential effects of alterations of H on neural network activation and connectivity. Correlation analyses between the alterations of HACC/HNAcc and activation maps and DCM estimates were performed. We found that the alterations of H predominantly correlated with fronto-hippocampal pathways and correlations were significant only in highIMP subjects. For example, alterations of HACC was associated with a decrease in neural activation in the right HC in combination with increased ACC-hippocampal connectivity. Alteration inHNAcc, in return, was related to an increase in bilateral prefrontal activation in combination with increased fronto-hippocampal connectivity. The findings, that the WI network was related to H alteration in highIMP subjects indicated that impulse control was not reduced per se but lacked consistency. Additionally, H has been used to describe long-term memory processes before, e.g., in capital markets, energy future prices, and human memory. Thus, current findings supported the relation of H toward memory processing even when further prominent cognitive functions were involved.

Chronic molecular hydrogen inhalation mitigates short and long-term memory loss in polymicrobial sepsis

The central nervous system (CNS) is one of the first physiological systems to be affected in sepsis. During the exacerbated systemic inflammatory response at the early stage of sepsis, circulatory inflammatory mediators are able to reach the CNS leading to neuroinflammation and, consequently, long-term impairment in learning and memory formation is observed. The acute treatment with molecular hydrogen (H2) exerts important antioxidative, antiapoptotic, and anti-inflammatory effects in sepsis, but little is known about the mechanism itself and the efficacy of chronic H2 inhalation in sepsis treatment. Thus, we tested two hypotheses. We first hypothesized that chronic H2 inhalation is also an effective therapy to treat memory impairment induced by sepsis. The second hypothesis is that H2 treatment decreases sepsis-induced neuroinflammation in the hippocampus and prefrontal cortex, important areas related to short and long-term memory processing. Our results indicate that (1) chronic exposure of hydrogen gas is a simple, safe and promising therapeutic strategy to prevent memory loss in patients with sepsis and (2) acute H2 inhalation decreases neuroinflammation in memory-related areas and increases total nuclear factor E2-related factor 2 (Nrf2), a transcription factorthat regulates a vast group of antioxidant and inflammatory agents expression in these areas of septic animals.

Is the middle cranial fossa a reliable predictor of temporal lobe volume in extant and fossil anthropoids?

We investigate the suitability of middle cranial fossa (MCF) size as a proxy for temporal lobe volume (TLV), examining the strength of the association between TLV and MCF metrics and assess the reliability predicting TLV in fossil anthropoids. The temporal lobe of the primate brain is a multimodal association cortex involved in long-term memory, auditory, and visual processing with unique specializations in modern humans for language comprehension. The MCF is the bony counterpart for the temporal lobe providing inferences for fossil hominin temporal lobe evolution. We now investigate whether the MCF is a suitable proxy for the temporal lobe. A sample of 23 anthropoid species (n = 232, including 13 fossil species) from computed tomography (CT) scans of ex vivo crania and magnetic resonance imaging (MRI) of the in vivo brain were generated into three-dimensional (3D) virtual models. Seven linear metrics were digitally measured on the right MCF with right TLV calculated from in vivo MRI. Regression analyses produced statistically significant correlations between TLV and all MCF metrics (r ≥ 0.85; p ≤ 0.0009) with TLV predictions within ±1 standard error and three MCF metrics (posterior-width, mid-length, and mid-width) the most reliable predictors of TLV with only one metric weakly associated with TLV. These findings indicate a strong association between the MCF and TLV, provide reliable predictors of fossil TLV that were previously unattainable, allow the inclusion of fragmentary fossil material, and enable inferences into the emergence of modern human temporal lobe morphology.

Exploring Senior High School Students’ Academic Writing Difficulties: Towards an Academic Writing Model

Undeniably, writing is an indispensable skill in different contexts of life. It is one of the pivotal components of education. With the advent of the K-12 Basic Education Curriculum, students are confronted with different academic writing tasks through the English for Academic and Professional Purposes and Practical Research courses. Despite the efforts of the educational sector to improve students’ writing skills, many students still experience difficulties in academic writing. Therefore, there is a need to fill the gap and advance an in-depth understanding of students’ academic writing difficulties. In order to satisfy the said aim, this Qualitative study grounds on Flower and Hayes’ (1981) Cognitive Process Theory of Writing. Focus group discussion of 14 purposively selected Grade 11 Senior High School students was carried out. The results expound on the different Academic Writing difficulties encountered by the participants in terms of the Task Environment, Writers’ Long-Term Memory and Writing Process. A model for teaching academic writing was formulated anchored on the identified difficulties. The model will benefit the teachers as it may serve as a guide in more effective and efficient teaching of academic writing.

Using Vocal Production to Improve Long-Term Verbal Memory in Adults with Intellectual Disability.

Individuals with intellectual disability (ID) typically show weak long-term memory (LTM) skills. Understanding verbal LTM processes and searching for effective mnemonics in this population is important, to improve intervention programs. The current study aimed to assess verbal LTM abilities of adults with mild ID of mixed etiologies, and to offer a simple memorization technique based on vocal production. Participants (n = 55) learned lists of different study materials (images of familiar and unfamiliar objects, written words, and sentences) by vocal production (saying or reading aloud) or by no-production (looking, listening, or reading silently). Memory tests followed. Better memory was found for vocally produced images of familiar objects, written words, and sentences. The results show that adults with mild ID can benefit from the relative distinctiveness of items at study. Hence, vocalization may be used in educational and therapeutic contexts for this population, improving memory performance.

Learning to suppress a distractor is not affected by working memory load

Where and what we attend to is not only determined by our current goals but also by what we have encountered in the past. Recent studies have shown that people learn to extract statistical regularities in the environment resulting in attentional suppression of high-probability distractor locations, effectively reducing capture by a distractor. Here, we asked whether this statistical learning is dependent on working memory resources. The additional singleton task in which one location was more likely to contain a distractor was combined with a concurrent visual working memory task (Experiment 1) and a spatial working memory task (Experiment 2). The result showed that learning to suppress this high-probability location was not at all affected by working memory load. We conclude that learning to suppress a location is an implicit and automatic process that does not rely on visual or spatial working memory capacity, nor on executive control resources. We speculate that extracting regularities from the environment likely relies on long-term memory processes.

Patent Highlights April–May 2019

Patent Highlights April–May 2019

Different Associations between Auditory Function and Cognition Depending on Type of Auditory Function and Type of Cognition.

Previous studies strongly suggest that declines in auditory threshold can lead to impaired cognition. The aim of this study was to expand that picture by investigating how the relationships between age, auditory function, and cognitive function vary with the types of auditory and cognitive function considered. Three auditory constructs (threshold, temporal-order identification, and gap detection) were modeled to have an effect on four cognitive constructs (episodic long-term memory, semantic long-term memory, working memory, and cognitive processing speed) together with age that could have an effect on both cognitive and auditory constructs. The model was evaluated with structural equation modeling of the data from 213 adults ranging in age from 18 to 86 years. The model provided good a fit to the data. Regarding the auditory measures, temporal-order identification had the strongest effect on the cognitive functions, followed by weaker indirect effects for gap detection and nonsignificant effects for threshold. Regarding the cognitive measures, the association with audition was strongest for semantic long-term memory and working memory but weaker for episodic long-term memory and cognitive speed. Age had a very strong effect on threshold and cognitive speed, a moderate effect on temporal-order identification, episodic long-term memory, and working memory, a weak effect on gap detection, and nonsignificant, close to zero effect on semantic long-term memory. The result shows that auditory temporal-order function has the strongest effect on cognition, which has implications both for which auditory concepts to include in cognitive hearing science experiments and for practitioners. The fact that the total effect of age was different for different aspects of cognition and partly mediated via auditory concepts is also discussed.

Where working memory meets long-term memory: The interplay of list length and distractors on memory performance.

Previous work regarding a counterintuitive benefit of increasing distractors on episodic long-term memory (LTM) has suggested that retrieval of memoranda in working memory (WM) after attention has been distracted may confer benefits to episodic LTM. The current study investigated 2 conceptions of how this may occur: either as an attentional refreshing of active memoranda within the focus of attention or as retrieval of a cohesive chunk of memoranda from outside the central component of WM. Given the literature suggesting that increasing the number of items to maintain in WM, or list length, incurs an attentional cost, the current study investigated whether increasing list length may reduce the beneficial impact of distractors on episodic LTM. In a series of three experiments, we manipulated list length and the number of distractors following the memoranda in a Brown-Peterson-like-span task. Despite profound negative effects of list length and distractors on initial recall, the results indicated that list length did not interact with the beneficial effect of distractors on final free recall of the items. Furthermore, final free recall was consistent across serial position, in line with the view that all of the memoranda are retrieved as a chunk after each distractor. These findings emphasize the notion that recovering inactive information from outside of the central component of WM may impact its long-term retention. The theoretical implications regarding how retrieval may be a means by which LTM processes influence WM are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Neuropsychological characteristics of benign multiple sclerosis patients: A two-year matched cohort study

BackgroundThe definition of benign multiple sclerosis (BMS) is still debated. It is mainly based on physical status, however, there is an attempt to involve cognitive functioning or paraclinical factors in order to avoid unnecessary long-term treatment with disease-modifying therapies and to identify these subjects in the early stages of the disease. Therefore the aim of our two-year follow-up study was to investigate the pattern of cognitive functioning and depression in patients with BMS compared to treated relapsing-remitting MS (RRMS) patients and healthy controls. MethodsA group of 22 BMS patients was tested against matched RRMS patients and healthy controls. All individuals underwent neuropsychological evaluation exploring mood and the cognitive domains most frequently impaired in MS. MS patients were retested at two-year follow-up. ResultsIn terms of cognitive functions there were no differences between BMS and RRMS patients either at baseline or at two-year follow-up. Compared to healthy controls BMS patients showed poorer performance in long-term visuo-spatial memory and information processing speed, whereas, complex attention, working memory, long-term verbal memory – despite slower verbal learning – and executive function were found to be intact. RRMS patients showed significant difference in complex attention, long-term visual memory and information processing speed. Cognitive impairment differed in the patient groups in terms of severity. Both patient groups were depressed compared to controls, but significant differences were found only between BMS and healthy individuals. ConclusionThe results of our study confirm that cognitive functions and mood can be affected in MS independent of disease course and disease modifying treatment. The “benign” label should be treated as only a reference to physical status and non-motor symptoms should be routinely monitored. Without receiving therapy it is an existing entity with longstanding minimal disability.

Time course of the physiological stress response to an acute stressor and its associations with the primacy and recency effect of the serial position curve.

Whether stress affects memory depends on which stress pathway becomes activated and which specific memory system is involved. The activation of the sympathetic nervous system (SNS), leads to a release of catecholamines. The activation of the hypothalamic-pituitary-adrenal (HPA) axis, leads to a release of glucocorticoids. In thus study, it was investigated whether SNS and/or HPA axis activation are associated with long-term memory (LTM) and/or working memory (WM) performance in humans. Thirty-three participants underwent the socially evaluated cold-pressor test. Salivary alpha-amylase (sAA) was used as a marker for the activation of the SNS and cortisol as marker for HPA axis activation. Memory was assessed by means of word lists with 15 words each. The primacy effect (i.e., the correctly recalled words from the beginning of the lists) of the serial position curve was considered as indicator for LTM. The recency effect (i.e., the correctly recalled words from the end of the lists) were used as estimator for WM performance. In sAA responders, the recency effect and, therefore, WM performance increased immediately after the stressor. This was not found in sAA non-responders. In cortisol responders, the primacy effect and, thus, LTM performance decreased 20 minutes after the stressor. No change in LTM performance was found in cortisol non-responders. Our study supports the assumptions that 1) SNS activation is associated with WM processes via stimulation of the prefrontal cortex, and 2) HPA axis activation is associated with LTM processes through interactions with the hippocampus.

Evidence for the incorporation of temporal duration information in human hippocampal long-term memory sequence representations

There has been much interest in how the hippocampus codes time in support of episodic memory. Notably, while rodent hippocampal neurons, including populations in subfield CA1, have been shown to represent the passage of time in the order of seconds between events, there is limited support for a similar mechanism in humans. Specifically, there is no clear evidence that human hippocampal activity during long-term memory processing is sensitive to temporal duration information that spans seconds. To address this gap, we asked participants to first learn short event sequences that varied in image content and interval durations. During fMRI, participants then completed a recognition memory task, as well as a recall phase in which they were required to mentally replay each sequence in as much detail as possible. We found that individual sequences could be classified using activity patterns in the anterior hippocampus during recognition memory. Critically, successful classification was dependent on the conjunction of event content and temporal structure information (with unsuccessful classification of image content or interval duration alone), and further analyses suggested that the most informative voxels resided in the anterior CA1. Additionally, a classifier trained on anterior CA1 recognition data could successfully identify individual sequences from the mental replay data, suggesting that similar activity patterns supported participants' recognition and recall memory. Our findings complement recent rodent hippocampal research, and provide evidence that long-term sequence memory representations in the human hippocampus can reflect duration information in the order of seconds.

A Functional Link Between Mental Representation in Long-Term Memory and Cognitive Performance in Working Memory.

Although there have been various attempts to identify the perceptual-cognitive mechanisms underlying the superior performance of skilled players over novices in sports, few studies have examined the relationship between mental representations and cognitive performance according to the skill levels of players. The purpose of this study was to investigate the functional link between mental representations in long-term memory and cognitive information processing ability in working memory by analyzing mental representation structure and cognitive performance according to skill level. Twenty male skilled and 25 male novice tennis players participated in this study. Structural dimensional analysis of mental representation was used to evaluate the mental representation structure of a tennis serve. In addition, cognition and movement chronometry was used to assess the cognitive performance of a tennis serve in working memory. Results of the representational analysis showed that the similarity of the skilled players to the standard representation structure was higher than that of novices. Furthermore, results in cognitive performance showed that the skilled players had a higher accuracy and shorter response time compared to the novices. Finally, a significant correlation between the adjusted Rand index and cognition movement chronometry accuracy was observed. Taken together, the mental representation structure and cognitive performance of the skilled players were superior to those of the novices, and mental representations were positively correlated with the accuracy of the cognitive information processing. These results imply that the degree of functional connection between working memory and long-term memory may be used as a perceptual-cognitive factor to explain improvement in performance.

Survival of the Fittest: Increased Stimulus Competition During Encoding Results in Fewer but More Robust Memory Traces.

Forgetting can be accounted for by time-indexed decay as well as competition-based interference processes. Although conventionally seen as competing theories of forgetting processes, Altmann and colleagues argued for a functional interaction between decay and interference. They revealed that, in short-term memory, time-based forgetting occurred at a faster rate under conditions of high proactive interference compared to conditions of low proactive interference. However, it is unknown whether interactive effects between decay-based forgetting and interference-based forgetting also exist in long-term memory. We employed a delayed memory recognition paradigm for visual indoor and outdoor scenes, measuring recognition accuracy at two time-points, immediately after learning and after 1 week, while interference was indexed by the number of images in a semantic category. We found that higher levels of interference during encoding led to a slower subsequent decay rate. In contrast to the findings in working-memory, our results suggest that a “survival of the fittest” principle applies to long-term memory processes, in which stimulus competition during encoding results in fewer, but also more robust memory traces, which decay at a slower rate. Conversely, low levels of interference during encoding allow more memory traces to form initially, which, however, subsequently decay at a faster rate. Our findings provide new insights into the mechanism of forgetting and could inform neurobiological models of forgetting.

Individual differences in long-term memory.

The literature on individual differences in long-term memory (LTM) is organized and reviewed. This includes an extensive review of the factor structure of LTM abilities as well as specific individual differences in criterial tasks such as free recall, paired associates recall, and recognition. It is demonstrated that individual differences in LTM abilities are represented by various lower order factors based on criterial tasks as well as by a more general higher-order LTM factor. These individual differences are linked with multiple different constructs including working memory, intelligence, and attention control. Individual differences in forgetting, interference control, false memory, testing effects, general retrieval abilities, and the influence of strategies are also examined. Overall, it is clear that there are substantial and robust individual differences in LTM abilities and that these abilities demonstrate important relations with other cognitive abilities. Future directions and an integration of individual differences in a general framework of memory are discussed, and it is suggested that combined experimental and correlational approaches are needed to better understand individual differences in LTM and that individual differences in LTM should be used to better test and revise theories of LTM processes. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Neural Processing of Repeated Search Targets Depends Upon the Stimuli: Real World Stimuli Engage Semantic Processing and Recognition Memory.

Recent evidence has suggested that visual working memory (VWM) plays an important role in representing the target prior to initiating a visual search. The more familiar we are with the search target, the more refined the representation of the target (or “target template”) becomes. This sharpening of the target template is thought to underlie the reduced response time (RT) and increased accuracy associated with repeatedly searching for the same target. Perhaps target representations transition from limited-capacity VWM to Long-Term Memory (LTM) as targets repeat. In prior work, amplitude of an event-related potential (ERP) component associated with VWM representation decreased with target repetition, broadly supporting this notion. However, previous research has focused on artificial stimuli (Landolt Cs) that are far removed from search targets in the real world. The current study extends this work by directly comparing target representations for artificial stimuli and common object images. We found VWM representation follows the same pattern for real and artificial stimuli. However, the initial selection of the real world objects follows a much different pattern than more typical artificial stimuli. Further, the morphology of nonlateralized waveforms was substantially different for the two stimulus categories. This suggests that the two types of stimuli were processed in fundamentally different ways. We conclude that object type strongly influences how we deploy attentional and mnemonic resources prior to search. Early attentional selection of familiar objects may facilitate additional LTM processes that lead to behavioral benefits not seen with more simplistic stimuli.

Potential Role of OERP as Early Marker of Mild Cognitive Impairment.

Olfactory impairment is present in up to 90% of patients with Alzheimer’s disease (AD) and is present in certain cases of mild cognitive impairment (MCI), a transient phase between normal aging and dementia. Subjects affected by MCI have a higher risk of developing dementia compared to the general population, and studies have found that olfactory deficits could be an indicator of whether such a conversion might happen. Following these assumptions, aim of this study was to investigate olfactory perception in MCI patients. We recruited 12 MCI subjects (mean age 70 ± 6.7 years) through the Alzheimer Assessment Unit (UVA Unite) of ASL Lecce (Italy), and 12 healthy geriatric volunteers (HS) as the control group (mean age 64 ± 6.0 years), all of whom were first evaluated via a panel of neuropsychological tests. Subjects were asked to perform an olfactory recognition task involving two scents: rose and eucalyptus, administrated in the context of an oddball task during EEG recordings. Olfactory event-related potential (OERP) components N1 and Late Positive Potential (LPC) were then analyzed as measures of the sensorial and perceptive aspects of the olfactory response, respectively. It was determined that, in the MCI group, both the N1 and LPC components were significantly different compared to those of the HS group during the execution of the oddball task. In particular, the N1 amplitude, was reduced, while the LPC amplitude was increased, indicating that a degree of perceptive compensation can occur when sensorial function is impaired. Further, a correlation analysis, involving OERP components and neuropsychological battery scores, indicated that impairment of olfactory perception may share common pathways with impairments of the spatial system and long-term memory processing.

Memory and exploratory behavior impairment in ovariectomized Wistar rats

BackgroundEstrogen deficiency is linked to changes in several physiological processes, but the extent to which it associates with cognitive changes in menopause context is controversial.RationaleWe evaluated the impact of ovariectomy on memory processes and normal exploratory behavior in Wistar rats.MethodsYoung adult rats (4–6 months) were either ovariectomized (OVX group) (N = 10), sham operated (N = 10), or untouched (naïve controls) (N = 8). Afterwards, they were monitored for 12 weeks during which their cognitive functions were evaluated at first week (S1), second (S2), every 3 weeks (S5, S8) and then at week 12 (S12) using: (i) object recognition test to evaluate the short-term and long-term non-spatial memory; (ii) the object placement test to assess the spatial memory; and (iii) normal exploratory behavior components like locomotor and vertical activities in an open field arena.ResultsMarked changes in ovariectomized rats were observed in long-term non-spatial memory (~ 40% change vs. naïve and sham, P < 0.001) and spatial memory (~ 30% change, P < 0.05) from S2. Instead, from S5 the exploratory behavior was affected, with decreases in line crossing and rearing episode numbers (~ 40% change, P < 0.01), and in the time spent in the center of open field arena (~ 60% change, P < 0.01).ConclusionsOur findings support the involvement of sex hormones in cognitive functions in female rats and suggest that controversy on the importance of cognitive affections in menopause context may emerge from differences between short-term and long-term memory processes.

Descriptive study of post-minor stroke cognitive defects (modified ranking scale ≤ 2), impact on quality of life and return to work

descriptive study of cognitive impairments in patients having presented a right-sided, left-sided or bilateral minor stroke (modified ranking scale ≤ 2), and evaluation of their impact on life quality and return to work. This study includes 47 patients having presented a minor stroke. Cognitive functions were evaluated in day hospital by neuropsychologists, ergotherapists and speech-therapists. These assessments were conducted between 6 and 24 months after the stroke, with evaluations of the patients’ executive functions, short- and long-term memory and information processing speed. The defects’ impact on everyday life was calculated with the MacNair and Kahn scale, the Reintegration to Normal Living Index (RNLI) and the Sickness Impact Profile-65 (SIP-65). Correlations between cognitive performances and everyday impacts were made. On the professional level, 73% of patients working before the stroke had not resumed their professional activity at the time of their evaluation. No patient having presented a left-sided stroke returned to full-time work. Regarding life quality, scores showed no significant difference comparable between the three groups. In the cohort, the RNLI averaged at 78.5%, the SIP-65 at 0.32, and the MacNair at 58.4/156. Concerning neuropsychological tests, the Montreal cognitive assessment (MOCA) score was < 26 for 54.6% of the patients, with a significant difference between the groups of bilateral and right-sided strokes, in favour of the latter. There was no significant difference between groups regarding the Virtual action planning supermarket (VAP-S). The Symbol Digit Modalities Test evaluated the information processing speed, with an oral score revealed pathological in 72.3% of the cohort, which is near ¾ of the patients. This study demonstrates the importance of cognitive impairments in minor stroke patients, as well as their impact on everyday life in terms of life quality and return to work. This shows the interest in implementing systematic post-stroke consultations in minor stroke patients.

Working memory capacity, short-term memory capacity, and the continued influence effect: A latent-variable analysis

Misinformation often affects inferences and judgments even after it has been retracted and discredited. This is known as the continued influence effect. Memory processes have been theorized to contribute to the continued influence effect, and much previous research has focussed on the role of long-term memory processes at the time misinformation is retrieved during inferential reasoning and judgments. Recently, however, experimental research has focussed upon the role of working memory (WM) processes engaged in the updating and integration of information, when the retraction is encoded. From an individual differences perspective, susceptibility to continued influence effects should be predicted by a person's WM abilities, if continued reliance on misinformation is influenced, at least in part, by insufficient integration of the initial misinformation and its subsequent retraction. Consequently, we hypothesized that WM capacity would predict susceptibility to continued influence effects uniquely and more substantially than short-term memory (STM) capacity. Participants (N = 216) completed a continued-influence task, as well as a battery of WM and STM capacity tasks. Based on a latent variable model, our hypothesis was supported (WM capacity: β = −0.36, p = .013; STM capacity: β = 0.22, p = .187). Consequently, we suggest that low WM capacity is a measurable “risk factor” for continued reliance on misinformation.